1. Phillip Chamberlin Solar Flares (303)492-9318 University of Colorado
Laboratory for Atmospheric and Space Physics (LASP)
(303)

2. Chamberlin - Solar Flares - REU 2009
Outline
Solar Atmosphere
Flux Tubes
Two Ribbon Flare
Cartoons
Movies
Irradiance Measurements of Flares
VUV
White Light
TSI
June 10, 2009
Chamberlin - Solar Flares - REU 2009

3. XUV, EUV, and FUV Solar Spectrum
Transition Region
From Lean (1997)
5700 K : Temp of “Solar Surface”
T_min: 4200 K - Optically thin to most emissions
June 10, 2009
Chamberlin - Solar Flares - REU 2009

4. Chamberlin - Solar Flares - REU 2009
Solar Images - Oct. 28, 2003
Chromosphere
H-Alpha
Corona
Photosphere
Transition Region
(Images courtesy of Big Bear Solar Observatory and SOHO EIT)
June 10, 2009
Chamberlin - Solar Flares - REU 2009

5. Chamberlin - Solar Flares - REU 2009
Flux Tubes
(Schrijver and Zwaan, 2000)
June 10, 2009
Chamberlin - Solar Flares - REU 2009

6. Chamberlin - Solar Flares - REU 2009
Flux Tubes
Initial rotating convection zone with weak vertical B-field lines
B-field lines concentrated in strands between convection cells to form Flux Tubes
Absence of B-field within convection cells due to B-field line reconnection
(Schrijver and Zwaan, 2000)
June 10, 2009
Chamberlin - Solar Flares - REU 2009

7. Chamberlin - Solar Flares - REU 2009
Emerging Flux
Solar Atmosphere
Active Regions
Balance between hydrostatic pressure and magnetic pressure causes the flux tubes to be less dense due to their stronger magnetic pressure buoyant flux tubes
Convection Zone
(Schrijver and Zwaan, 2000)
June 10, 2009
Chamberlin - Solar Flares - REU 2009

8. Chamberlin - Solar Flares - REU 2009
Emerging Flux (Title, 2004)
June 10, 2009
Chamberlin - Solar Flares - REU 2009

9. Chamberlin - Solar Flares - REU 2009
June 10, 2009
Chamberlin - Solar Flares - REU 2009

10. Chamberlin - Solar Flares - REU 2009
Phases of Solar Flares
(Adapted from Schrijver and Zwaan, 2000)
Microwave Radio (~3000 MHz)
Radio ( MHz)
H-alpha (656.2 nm)
Broadband EUV ( nm)
Soft X-rays (< 10 keV)
X-rays (10-30 keV)
Main Phase
Hard X-rays (> 30 keV)
Impulsive Phase
Note: Soft X-rays: nm,
Hard X-rays: nm
Precursor
June 10, 2009
Chamberlin - Solar Flares - REU 2009

11. Two-Ribbon Reconnection
Thick-target model produces Bremsstrahlung radiation in the transition region and chromosphere due to their much higher densities - Impulsive Phase!
Reconnection after instability accelerates material down loop. Observed Hard X-ray (and EUV?) enhancements at loop top.
[Ashwanden,
2004]
No enhanced emissions during the impulsive phase in the corona due to its low density.
Energy deposited during the impulsive phase heats the plasma up and rises (chromospheric evaporation) to fill flux tube - Gradual Phase!
June 10, 2009
Chamberlin - Solar Flares - REU 2009

12. Jets Evidence of Small-Scale Reconnection?
June 10, 2009
Chamberlin - Solar Flares - REU 2009

13. Chamberlin - Solar Flares - REU 2009
Two-Ribbon Flare
Eruption when some critical limit is reached
Triggered by Emerging Flux?
Continued thermal heating and formation of post-flare loops
“Stretching” of field lines
(Priest, 1981)
June 10, 2009
Chamberlin - Solar Flares - REU 2009

14. Chamberlin - Solar Flares - REU 2009
Phases of Solar Flares
(Adapted from Schrijver and Zwaan, 2000)
Microwave Radio (~3000 MHz)
Radio ( MHz)
H-alpha (656.2 nm)
Broadband EUV ( nm)
Soft X-rays (< 10 keV)
X-rays (10-30 keV)
Main Phase
Hard X-rays (> 30 keV)
Impulsive Phase
Note: Soft X-rays: nm,
Hard X-rays: nm
Precursor
June 10, 2009
Chamberlin - Solar Flares - REU 2009

15. Chamberlin - Solar Flares - REU 2009
Two-Ribbon Flare
Impulsive Phases for Each Loop
Post-Flare Loops
(Somov, 1992)
June 10, 2009
Chamberlin - Solar Flares - REU 2009

16. Flares drive waves in the photosphere
June 10, 2009
Chamberlin - Solar Flares - REU 2009

17. Chamberlin - Solar Flares - REU 2009
X28 Flare, Nov 4, 2003
June 10, 2009
Chamberlin - Solar Flares - REU 2009

18. Hinode SOT Observes Flare
June 10, 2009
Chamberlin - Solar Flares - REU 2009

19. SOHO (UV) and SORCE XPS (XUV) Observations
June 10, 2009
Chamberlin - Solar Flares - REU 2009

20. Chamberlin - Solar Flares - REU 2009
Phases of Solar Flares
(Adapted from Schrijver and Zwaan, 2000)
Microwave Radio (~3000 MHz)
Radio ( MHz)
H-alpha (656.2 nm)
Broadband EUV ( nm)
Soft X-rays (< 10 keV)
X-rays (10-30 keV)
Main Phase
Hard X-rays (> 30 keV)
Impulsive Phase
Note: Soft X-rays: nm,
Hard X-rays: nm
Precursor
June 10, 2009
Chamberlin - Solar Flares - REU 2009

21. VUV Irradiance Increases Dominate Flare Variations
VUV irradiance ( nm) accounts for only 0.007% of quite Sun Total Solar Irradiance (TSI)
VUV irradiance accounts for 30-70% of the increase in the TSI during a flare [Woods et al., 2006]
June 10, 2009
Chamberlin - Solar Flares - REU 2009

22. Flare/Pre-Flare Irradiance Ratio
Transition region emissions increased by up to a factor of 10 during the impulsive phase
EUV irradiance increased by a factor of 2 during the gradual phase
Flare Variations were as large or larger than the solar cycle variations for the Oct 28, 2003 flare
June 10, 2009
Chamberlin - Solar Flares - REU 2009

23. Chamberlin - Solar Flares - REU 2009
X-Ray Classification
Due to the large, order-of-magnitude increases in the soft X-rays makes for an ideal and sensitive classifications of the magnitude of flares
June 10, 2009
Chamberlin - Solar Flares - REU 2009

24. Chamberlin - Solar Flares - REU 2009
White Light Flare
“Carrington Flare” September 1, 1859
Carrington (M.N.R.A.S, 20, 13, 1860)
One of the largest flares believed to have occurred in the past 200 years
Two-Ribbon flare
June 10, 2009
Chamberlin - Solar Flares - REU 2009

25. Flares in Photosphere and Chromosphere
Hinode SOT Observations
June 10, 2009
Chamberlin - Solar Flares - REU 2009

26. Chamberlin - Solar Flares - REU 2009
X17 flare observed in TSI
First detection of flare in TSI record (G. Kopp, 2003)
Figures from G. Kopp, arranged by T. Woods
June 10, 2009
Chamberlin - Solar Flares - REU 2009

27. Chamberlin - Solar Flares - REU 2009
Conclusions
Multiple images and spectral measurements are key to understanding energetic of flares
New measurements (Hinode, Stereo, EVE, AIA, etc.) will lead to a much greater understanding of these processes
Biggest mystery still is the ‘trigger’
Another topic to that is not fully understood is the relationship of CMEs and Flares
June 10, 2009
Chamberlin - Solar Flares - REU 2009

28. Chamberlin - Solar Flares - REU 2009
Extra Slides
June 10, 2009
Chamberlin - Solar Flares - REU 2009

29. Chamberlin - Solar Flares - REU 2009
Simple Loop Flare
Existing Flux Loop that Brightens
TRANSITION REGION
CORONA
CHROMOSPHERE
PHOTOSPHERE
-Most Common Type
-Are these an actual separate type of flare?
-Only Enhanced Internal Motions
(Priest, 1981)
June 10, 2009
Chamberlin - Solar Flares - REU 2009

30. Chamberlin - Solar Flares - REU 2009
Hinode SOT Movie #2
June 10, 2009
Chamberlin - Solar Flares - REU 2009

31. Flares Cause Sudden Atmospheric Changes
GRACE daytime density (490 km)
Increased neutral particle density in low latitude regions on the dayside.
Sudden Ionospheric Disturbances (SIDs) lead to Single Frequency Deviations (SFDs).
Cause radio communication blackouts
Cause increased error in GPS accuracy
Latitude (Deg)
2003 Day of Year
(E. Sutton, 2005)
Sudden increase in the dayside density at low latitude regions due to the X17 solar flare on October 28, 2003
June 10, 2009
Chamberlin - Solar Flares - REU 2009